Dynamic tdd data channel transmission method and apparatus for wireless communication system

ABSTRACT

A method by a terminal, a method by a base station, a terminal, and a base station are provided. The method by the terminal includes receiving system information including first time division duplex (TDD) configuration information; receiving control information via a higher layer signaling; monitoring a physical downlink control channel (PDCCH) in a first subframe identified based on the control information; and identifying second TDD configuration information based on the monitoring result. The method by the base station includes transmitting system information including first time division duplex (TDD) configuration information; transmitting control information via a higher layer signaling; transmitting downlink control information on a physical downlink control channel (PDCCH) in a first subframe identified based on the control information, wherein the downlink control information is used to identify second TDD configuration information.

PRIORITY

This continuation application claims priority under 35 U.S.C. §120 toU.S. patent application Ser. No. 13/478,804, filed on May 23, 2012 inthe United States Patent and Trademark Office, and is now issued as U.S.Pat. No. 9,185,668 on Nov. 10, 2015, which claimed priority under 35U.S.C. §119(a) to Korean Patent Application No. 10-2011-0048303, whichwas filed in the Korean Intellectual Property Office on May 23, 2011,the contents of each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a data channel transmissionmethod and apparatus for a wireless communication system operating in adynamic Time Division Duplex (TDD) mode.

2. Description of the Related Art

Orthogonal Frequency Division Multiplexing (OFDM) is a technique fortransmitting data using multiple carriers, i.e. a multi-carriertransmission scheme, which converts a serial symbol stream to parallelsymbol sets that are transmitted on the orthogonal multiple carriers.

The OFDM technique began in the late 1950's with the Frequency DivisionMultiplexing (FDM) for military communication purposes, and OFDM usingorthogonal overlapping multiple subcarriers was later developed butinitially was not widely used due to the difficulty of implementingorthogonal modulations between multiple carriers. However, with theintroduction in 1971 of the use of a Discrete Fourier Transform (DFT)for implementation of the generation and reception of OFDM signals, byWeinstein, the OFDM technology has rapidly developed. Additionally, theintroduction of a guard interval at the start of each symbol and use ofcyclic prefix (CP) overcomes the negative effects caused by multipathsignals and delay spread.

Due to these technical advances, the OFDM technology is now applied invarious digital communications fields such as Digital Audio Broadcasting(DAB), Digital Video Broadcasting (DVB), Wireless Local Area Network(WLAN), and Wireless Asynchronous Transfer Mode (WATM), based on theintroduction of various digital signal processing technologies such asFast Fourier Transform (FFT) and Inverse Fast Fourier Transform (IFFT).

OFDM is similar to FDM but is much more spectrally efficient forachieving high-speed data transmission by orthogonally overlappingmultiple subcarriers. Due to the spectral efficiency and robustness tothe multipath fading, OFDM has been considered as a prominent solutionfor improved broadband data communication systems. Other advantages ofOFDM are to control the Inter-Symbol Interference (ISI) using the guardinterval and reduce the equalizer complexity in view of hardware as wellas spectral efficiency and robustness to the frequency selective fadingand multipath fading. OFDM is also robust to noise impulses and thus maybe employed in various communication systems.

In OFDM, modulation signals are located in two-dimensionaltime-frequency resources, which are divided into different OFDM symbolsand are orthogonal with each other. Resources on the frequency domainare divided into different tones, and are also orthogonal with eachother. That is, the OFDM scheme defines one minimum unit resource bydesignating a particular OFDM symbol on the time domain and a particulartone on the frequency domain, and the unit resource is called a ResourceElement (RE). Since different REs are orthogonal with each other,signals transmitted on different REs can be received without causinginterference to each other.

A physical channel is defined on the physical layer for transmittingmodulation symbols obtained by modulating one or more coded bitsequences. In an Orthogonal Frequency Division Multiple Access (OFDMA)system, a plurality of physical channels can be transmitted depending onthe usage of the information sequence or receiver. The transmitter andreceiver negotiate the RE on which a physical channel is transmitted,which is a process called mapping.

High-speed, high-quality wireless data services are generally hinderedby the channel environment, which suffers from frequent changes due toadditive white Gaussian noise (AWGN) and power variation of receivedsignals, caused by such instances as a fading phenomenon, shadowing, aDoppler effect from terminal movement and a frequent change in terminalvelocity, and interference by other users or multipath signals.Therefore, in order to support high-speed, high-quality wireless dataservices, there is a need to efficiently overcome the above channelquality degradation factors.

SUMMARY OF THE INVENTION

In order to solve the problems of the prior art, the present inventionprovides a method and apparatus for transmitting data in the wirelesscommunication system operating in TDD mode that is capable of optimizingcommunication dynamically in adaptation to the uplink and downlinktraffic variations by dividing a subframe into a semi-static regioncarrying the control channel and a dynamic region that can be used foruplink and/or downlink data channels according to the uplink anddownlink data amount.

In accordance with an aspect of the present invention, a method by aterminal is provided. The method includes receiving system informationincluding first time division duplex (TDD) configuration information;receiving control information via a higher layer signaling; monitoring aphysical downlink control channel (PDCCH) in a first subframe identifiedbased on the control information; and identifying second TDDconfiguration information based on the monitoring result.

In accordance with an aspect of the present invention, a method by abase station is provided. The method includes transmitting systeminformation including first time division duplex (TDD) configurationinformation; transmitting control information via a higher layersignaling; transmitting downlink control information on a physicaldownlink control channel (PDCCH) in a first subframe identified based onthe control information, wherein the downlink control information isused to identify second TDD configuration information.

In accordance with an aspect of the present invention, a terminal isprovided. The terminal includes a transceiver configured to transmit andreceive a signal; a controller configured to receive system informationincluding first time division duplex (TDD) configuration information,receive control information via a higher layer signaling, monitor aphysical downlink control channel (PDCCH) in a first subframe identifiedbased on the control information, and identify second TDD configurationinformation based on the monitoring result.

In accordance with an aspect of the present invention, a base station isprovided. The base station includes a transceiver configured to transmitand receive a signal; a controller configured to transmit systeminformation including first time division duplex (TDD) configurationinformation, transmit control information via a higher layer signaling,and transmit downlink control information on a physical downlink controlchannel (PDCCH) in a first subframe identified based on the controlinformation, wherein the downlink control information is used toidentify second TDD configuration information.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention will bemore apparent from the following detailed description in conjunctionwith the accompanying drawings, in which:

FIG. 1 illustrates a conceptual architecture of a wireless communicationsystem to which the present invention is applied;

FIG. 2 illustrates the structure of a frame for use in a conventionalTDD system;

FIG. 3 illustrates a structure of the flexible subframe for use in thedynamic TDD data channel transmission method to which the presentinvention is applied;

FIG. 4 illustrates a structure of an adaptive TDD radio frame for usedin the dynamic TDD data channel to an embodiment of the presentinvention;

FIG. 5 illustrates the transmission-reception relationship of thedynamic TDD data channel of the dynamic TDD data channel transmissionmethod according to an embodiment of the present invention;

FIG. 6 illustrates relationship among control, acknowledgement, and datachannels when the dynamic subframe is used for uplink transmissionaccording to an embodiment of the present invention;

FIG. 7 illustrates a structure of a subframe configured for actual datatransmission in the dynamic data region in the dynamic TDD datatransmission method according to an embodiment of the present invention;

FIG. 8 illustrates an eNB procedure of the dynamic TDD data channeltransmission method according to an embodiment of the present invention;

FIG. 9 illustrates a UE procedure of the dynamic TDD data channeltransmission method according to an embodiment of the present invention;

FIG. 10 illustrates a configuration of the eNB according to anembodiment of the present invention; and

FIG. 11 illustrates a configuration of the UE according to an embodimentof the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention are described with reference to theaccompanying drawings in detail. Detailed descriptions of well-knownfunctions and structures incorporated herein may be omitted for the sakeof clarity and conciseness.

Although the following description is directed to Long Term Evolution(LTE) and LTE-Advanced (LTE-A) systems, the present invention can beapplied to other TDD-based radio communication systems operating withbase station scheduling without addition or subtraction.

The LTE system is a representative system adopting OFDM in the downlinkand Single Carrier-Frequency Division Multiple Access (SC-FDMA) in theuplink. An LTE system can be configured to operate in FDD mode in whichone of two frequency bands is used for downlink transmission and theother for uplink or TDD mode in which one frequency band is timedivision duplexed into one channel for downlink transmission and theother for uplink transmission.

In TDD mode, the uplink and downlink are switched according to a rule,and the LTE defines total 7 TDD radio frame configurations among whichone is selected and then maintained virtually the same. In TDD mode, ifthe cells are set with different configurations, they are likely to havefailed transmission/reception due to inter-cell interference. Thus, allof the cells deployed within a certain area must be set with the sameTDD configuration to acquire synchronization for uplink and downlinktransmissions.

A subframe of the LTE system has a length of 1 ms in a time domain andthe entire LTE transmission bandwidth in frequency domain and can bedivided into two time slots. The LTE transmission bandwidth consists ofa plurality of Resource Blocks (RBs), each of which being a basic unitof resource allocation. Each RB consists of 12 consecutive tones in thefrequency domain and 14 consecutive OFDM symbols in the time domain. Thesubframe can include a control channel region for transmitting controlchannels and/or a data channel region for transmitting data channels.The control and/or data channel regions carry Reference Signals (RSs)for use in channel estimation.

Meanwhile, the control channel region for a legacy UE is arranged at thebeginning of the subframe in the time domain. That is, the controlchannel region can be composed of L OFDM symbols at the beginning of thesubframe, where L can be set to 1, 2, or 3. When using Multi-MediaBroadcast over a Single Frequency Network (MBSFN) subframe for carryingbroadcast information, L is 2. Regarding the MBSFN subframe, the UE canreceive the control channel region of the corresponding subframe but notthe data channel region.

Research has recently been focused on LTE-A, which has evolved from LTE.The LTE-A system operating in TDD mode cannot meet the variation of datatraffic dynamically once the TDD radio frame configuration has beendetermined as described above. This is because the downlink subframecannot be used for uplink transmission even when there is no downlinktraffic while the uplink traffic increases. Extensive research is beingconducted to solve this problem, which is likely to occur in thehierarchical cellular environment.

FIG. 1 illustrates a conceptual architecture of a wireless communicationsystem to which the present invention is applied. As shown in FIG. 1,the macro cells and picocells are deployed hierarchically in the samearea.

Referring to FIG. 1, reference number 101 denotes macrocells, andreference number 102 denotes picocells. Typically, the picocell operatesat low transmit power as compared to the macrocell and is deployed at anarea with high traffic density within the macrocell. The high trafficdensity area indicates a region where the data traffic to be processedvaries in time.

For example, when a plurality of users receive downlink data andcommunicate through Voice over IP (VoIP), the UE is transmitting data inthe uplink while receiving a large amount of data in the downlink. Inthis case, it is preferred for the system to configure the TDD radioframe with a relatively large number of subframes for downlinktransmission while reducing the number of subframes for uplinktransmission. With the conventional system configuration, however, it isdifficult to meet the situation in which it is necessary to increase theuplink transmission resource for handling the abrupt increase of thedata or VoIP signal to be transmitted in uplink.

FIG. 2 illustrates the structure of a frame for use in a conventionalTDD system.

Referring to FIG. 2, a radio frame 201 spans 10 ms and consists of twohalf-radio frames 202. Each half-frame 202 consists of 5 subframes 203.The radio frame consists of 10 subframes, and each subframe has a lengthof 1 msec. The 10 subframes 203 can be set respectively according to oneof a total 7 TDD configurations as shown in Table 1. In configuration 0of Table 1, the 0^(th) and 5^(th) subframes are marked with “D” forindicating the downlink subframe, the 2^(nd), 3^(rd), 4^(th), 7^(th),and 8^(th) subframes are marked with “U” for indicating the uplinksubframe, and 1^(st) and 6^(th) are marked with “S” for indicating aspecial subframe 204.

The special subframe 204 consists of a downlink part (DwPTS), a GuardPeriod (GP), and an uplink part (UpPTS). The DwPTS is for transmittingdownlink control and data channel, the GP is not a carrier, and UpPTS isfor transmitting an uplink signal. Since the special subframe 204 has asmall uplink region, it is used for PRACH and SRS transmission but notas a data and control channel. The GP is configured to secure the timenecessary for switching from downlink transmission to uplink reception.

TABLE 1 Downlink- Uplink- to- downlink Uplink config- Switch-pointSubframe number uration periodicity 0 1 2 3 4 5 6 7 8 9 0  5 ms D S U UU D S U U U 1  5 ms D S U U D D S U U D 2  5 ms D S U D D D S U D D 3 10ms D S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D DD D D 6  5 ms D S U U U D S U U D

Referring to all of the TDD configuration information, there aresubframes 203 configured for transmission in one direction fixedlyregardless of the TDD configuration. The 0^(th), 1^(st), 5^(th), and6^(th) subframes are maintained in transmission direction regardless ofthe TDD configuration. The remaining subframes can be changed intransmission direction according to the TDD configuration. In the MBSFNsubframe, the 2^(nd), 3^(rd), 4^(th), 7^(th), 8^(th), and 9^(th)subframes can be used with the exception of the aforementioned 0^(th),1^(st), 5^(th), and 6^(th) subframes since the excluded subframes areused to transmit a synchronization signal such as Physical BroadcastCHannel (PBCH), Primary Synchronization Signal (PSS), and SecondarySynchronization Signal (SSS).

FIG. 3 illustrates a structure of the flexible subframe for use in thedynamic TDD data channel transmission method to which the presentinvention is applied.

Referring to FIG. 3, once the TDD radio subframe is configured in thelegacy LTE system, it is not changed by the data traffic amount. In thelegacy LTE system, it takes more than 80 msec to change theconfiguration even though there is TDD interference from neighbor cells.In order to switch between uplink and downlink subframes dynamically,although a method for use of a certain uplink or downlink subframe maybe used, these methods may cause significant system problems.

When switching from a certain uplink subframe 301 to a downlink subframe303, following problems may take place. First, in the real communicationenvironment, the switching occurs from downlink to uplink for processinga large amount of downlink traffic and sporadic uplink burst traffic.However, the switching from uplink to downlink is not appropriate forthe real communication environment since it is necessary to configure aTDD radio frame having a large amount of uplink resource.

Second, the uplink subframe is associated with an uplink transmissionprocess of the UE such that a specific downlink control channel islinked to the uplink subframe to transmit the control channel for theuplink data channel and an acknowledgement channel. Accordingly, if acertain uplink subframe disappears, the UE loses uplink data process andit is impossible to change a certain uplink subframe for a downlinksubframe until the UE's uplink retransmission is completed. Accordingly,it is difficult to dynamically meet the traffic variation. Further, inorder for the UE to check the subframe for use in the downlink, it isnecessary to receive scheduling information such that when there is afalse alarm in which the UE misinterprets scheduling information, thiscauses collision with the UE receiving a signal in the downlink,resulting in transmission/reception failure.

When using a certain downlink subframe 302 for uplink transmission asdenoted by reference number 304, the following problems may occur.First, all of the UEs receive a channel using reference signals receivedon the downlink region carrying the common reference signals. Thus, if acertain downlink subframe is used for uplink transmission, all of theUEs in the cell may not estimate the reference signal accurately and maylose the link between the UE and the eNB.

Second, similar to when the uplink subframe is used as downlinksubframe, the uplink subframe is associated with an uplink transmissionprocess of the UE such that a specific downlink control channel islinked to the uplink subframe to transmit the control channel for theuplink data channel and an acknowledgement channel. Accordingly, if acertain downlink subframe disappears, the UE loses the uplink dataprocess such that, until the UE's uplink retransmission ends completely,a certain uplink subframe for a downlink subframe cannot be changed.

There is therefore a need of a method for switching between the uplinkand downlink in adaptation to the traffic variation without compromisingthe UE's reference signal measurement as well as the UE'stransmission/reception process.

FIG. 4 illustrates a structure of an adaptive TDD radio frame for use inthe dynamic TDD data channel according to an embodiment of the presentinvention.

Referring to FIG. 4, the system checks the static region 401 byreferencing the TDD radio frame configuration information and determinesthe proposed dynamic data region by referencing the MBSFN subframeconfiguration information. In this case, the 2^(nd), 3^(rd), 4^(th),7^(th), 8^(th) and 9^(th) subframes are candidate subframes that can beconfigured, when used for downlink transmission, as flexible subframesfor dynamic data transmission. The candidate subframes can appearcontiguously or discretely. The system transmits the information on thedynamic data channel actually available for the dynamic datatransmission among the candidate subframes, and the UE uses thecorresponding region for dynamic data transmission.

If there is no dynamic data channel information, all of the MBSFNsubframes can be used as dynamic data channel with the notification onwhether the dynamic data channel is used in the system information. Thedynamic data channel information includes the transmission/receptiontiming information on the control channel and acknowledgement channelfor the uplink and downlink processes related to the dynamic datachannel, and this information can be retained by the UE rather thansignaled by the system. The candidate subframe for dynamic transmissionis divided into a semi-static control region 402 and a dynamic dataregion 403. The semi-static control region is for transmitting controlchannel from the eNB to the UE and can be changed semi-statically basedon the MBSFN configuration information and dynamic data channelinformation.

The dynamic data region 403 is for transmitting actual data and can beused as a downlink data channel for transmitting a large amount ofdownlink traffic or an uplink data channel for transmitting increaseduplink data transmission according to the traffic variation in the cell.Whether to configure the dynamic data region 403 for downlinktransmission is determined depending on the existence of the downlinkcontrol channel received in the semi-static region of the same MBSFNsubframe. When transmitting the downlink control channel for the UE inthe semi-static control region 402, the eNB transmits the data channelscheduled in the corresponding region.

Since the corresponding region is the MBSFN subframe and carries acommon reference signal, the data channel is transmitted using DMRS. Inorder to use the dynamic data region for uplink transmission, the eNBtransmits uplink scheduling received in a certain linked downlinkcontrol channel region. Upon receipt of the uplink scheduling in thelinked downlink control channel region, the linked dynamic data region402 is used for uplink transmission, and the eNB stops transmission toreceive the signal from the UE. This frame structure overcomes theshortcoming of the method described with reference to FIG. 3.

FIG. 5 illustrates the transmission-reception relationship of thedynamic TDD data channel of the dynamic TDD data channel transmissionmethod according to an embodiment of the present invention. FIG. 5illustrates how to overcome the shortcoming of the scheduling andreference signal measurement using the semi-static control region anddynamic data region disclosed in the present invention.

FIG. 5 relates to a technique for guaranteeing control channeltransmission of the eNB regardless of the change in data region. Thesemi-static region 501 and 503 can be used for transmitting uplinkscheduling information, downlink scheduling information, and anacknowledgement channel. Since the acknowledgement channel 503 and 507corresponding to the uplink transmission linked to the correspondingdynamic data channel can always be transmitted regardless of thedownlink transmission 502 of the dynamic data channel and the uplinkgrant 506, it is possible to use the dynamic data region even when theUE's transmission process is terminated.

Since MBSFN is available only in the downlink and the disclosedtechnique is for using the downlink resource for uplink transmission, itcan be applied to the system having a downlink-dominant traffic patternwith sporadic uplink burst traffic. Since the MBSFN subframe carries thecommon reference signal only in the control channel with a blank dataregion, it is not used for common reference signal-based channelestimation such that, even though the corresponding region is used foruplink transmission, it does not influence the reference signalmeasurement. Thus, the UE's reception performance is not affected.

Although it is assumed that the UE has received the uplink schedulingcontrol channel 505, the eNB can transmit the downlink control channelagain in the control channel region 501 regardless of a false alarm soas to reduce the false alarm probability. If it is assumed that thefalse alarm occurs at a probability of p (p<0) as usual, the false alarmprobability becomes p*p when using the disclosed method, therebyovercoming the false alarm problem.

FIG. 6 illustrates relationship among control, acknowledgement, and datachannels when the dynamic subframe is used for uplink transmissionaccording to an embodiment of the present invention.

Referring to FIG. 6, when the system instructs one TDD radio frameconfiguration to all of the UEs, the UEs transmit and receive the datacan controls channels at transmission/reception timings. This is appliedto both the uplink and downlink data transmission. For example, if thesystem is configured with the configuration 4 601, the UEs can have upto 2 uplink data processes based on the timings 602 and 603. If it isrequired to instantly allocate further uplink resources, the eNB can usea certain downlink resource that can be configured for MBSFN based ontwo methods.

One method is to configure the subframes chanted by applying a flexiblesubframe as shown in Table 1, and the other method is to configure thesubframes according to a configuration not shown in Table 1. When usingthe configurations shown in Table 1, e.g. the fourth subframe 604 isused, the configuration is identical with the TDD radio frameconfiguration 4 in Table 1 from the reference point of the timingavailable for entire uplink transmission. In this case, since the UEknows the transmission-reception configuration of the channels as shownin Table 1, it recognizes that other configurations in Table 1 can beapplied such that the UE can use the transmission/reception timing ofconfiguration 4 of Table 1.

If the dynamic subframe is applied to change the configuration foranother configuration of Table 1, it can be possible to change only theprocess linked to the changed uplink subframe, and the other method canbe of changing the process linked to the uplink subframe for a newconfiguration. It is also possible to add a 1-bit field to the controlchannel to indicate the configuration among normal the TDD radio framestructure or a temporarily applied TDD radio frame configuration.

The configuration with change of the dynamic subframe may not beincluded in Table 1, such as when the ninth subframe 606 is used as thedynamic subframe. In this case, a rule is applied such that the controlchannel is transmitted at the subframe appearing first after foursubframes since the dynamic subframe in the downlink control channelappears first before 4 dynamic subframes in consideration of the receiptof the control channel.

FIG. 7 illustrates a structure of a subframe configured for actual datatransmission in the dynamic data region in the dynamic TDD datatransmission method according to an embodiment of the present invention.

Referring to FIG. 7, reference numeral 701 denotes the timing at whichthe dynamic data region is used for downlink transmission. Referencenumeral 702 denotes the semi-static region for transmitting a controlchannel with the common reference signal. Reference numeral 703 denotesthe region that is originally blank or carries a broadcast channel and,in the present invention, used for downlink data channel transmissionwith the Dedicated Modulation Reference Signal (DM-RS). Referencenumeral 704 denotes the timing at which the dynamic data channel is usedfor uplink data channel transmission.

Even at the uplink data transmission timing, the first one or twosymbols are used for downlink transmission as denoted by the referencenumeral 702, and this region is used for the UE to transmit the controlchannel using the common reference signal. Afterward, in order to switchto the uplink, the eNB stops transmission and the UE transmits thesignal as denoted by reference numeral 708 in consideration of the UE'slink switching timing 705 and the eNB's reception synchronization timing706. When the first two symbols are used for control channeltransmission, a total 11 symbols can be used for uplink data channel asdenoted by reference numeral 708 and, for this purpose, it is necessaryto change the position of the reference signal.

The present invention discloses a subframe structure in which the 5^(th)and 11^(th) symbols are used for the reference signal with a total 11symbols for data transmission. In this case, the number of availablesymbols in the dynamic data region is 11 and is used at the uplinkchannel interleaver. This is identical to when the Sounding ReferenceSignal (SRS) is transmitted in the subframe with an extended CyclicPrefix (CP), and the column set of the channel interleaver for rankinformation is {0, 3, 5, 8}. The column set for Hybrid Automatic RepeatReQuest ACKnowledgement (HARQ-ACK is {1, 2, 6, 7} and, in this case, thestructure is identical with the case of transmission SRS in the subframewith extended CP. When the dynamic data channel is used as the uplinkdata channel, the UE's acknowledgement channel is not transmitted and,since the entire band is used for the data channel so as to compensatefor the loss of the downlink control channel in a few symbols at thebeginning, the system performance is not degraded.

FIG. 8 illustrates an eNB procedure of the dynamic TDD data channeltransmission method according to an embodiment of the present invention.

Referring to FIG. 8, the eNB transmits the system information includingthe TDD radio frame configuration information and the cell's MBSFNsubframe configuration information to the UE at step 802. Next, the eNBgenerates a dynamic TDD data region information for use of the dynamicdata channel in the MBSFN subframe and transmits the data regioninformation to the UE through higher layer signaling at step 803. TheeNB determines whether the dynamic data region of the m^(th) subframe asMBSFN subframe is used for uplink transmission at step 804.

If it is determined that the dynamic data region of the m^(th) subframeis used for uplink transmission at step 804, the eNB transmits uplinkscheduling control channel at the control channel region of the(m-k)^(th) subframe at step 805. Here, k denotes the time intervaldefined according to the configurations listed in Table 1, and any casewhich is not included in Table 1 indicates the subframe of which index(m-k) is greater than 4 and which is a downlink subframe. Accordingly,the eNB transmits the control channel at the m^(th) subframe at step 806and then switches to the reception mode at step 807. At this time, theeNB can transmit the channel allocation information for the data channelof the m^(th) subframe, and the channel allocation information for thedata channel of the uplink subframe linked to the m^(th) subframe. Next,the eNB receives the UE's Physical Uplink Shared Channel (PUSCH) datachannel in the shortened format based on the scheduling result at step808. At this time, the eNB can receive the data channel using the uplinkreference signal in the 5^(th) and 11^(th) symbols among 0^(th) to11^(th) symbols of m^(th) subframe.

Otherwise, if it is determined that the dynamic data region of m^(th)subframe is used for downlink transmission at step 804, the eNBtransmits downlink scheduling information at the control channel regionof m^(th) subframe at step 809. Next, the eNB transmits the controlchannel in the m^(th) subframe at step 810. At this time, the eNB cantransmit the channel allocation information for the data channel in them^(th) subframe. Afterward, the eNB transmits the data channelUE-specific reference signal at step 811. The UE specific referencesignal is a Dedicated Modulation Reference Signal (DMRS).

That is, the eNB divides an MBSFN subframe into a semi-static region anda dynamic region among a plurality of subframes multiplexed in a radioframe temporally. The eNB transmits a control signal in the semi-staticregion and receives uplink data or transmits downlink data in thedynamic region. At this time, the eNB can receive the uplink data ortransmit the downlink data in the dynamic region according to thecontrol signal in the semi-static region. The eNB also can receive theuplink data or transmit the downlink data in the dynamic region of theMBSFN subframe according to the control signal of the static subframelinked with the MBSFN subframe among the subframes. The eNB can alsoreceive the uplink data in the static uplink subframe linked with theMBSFN subframe among the subframes according to the control signal inthe semi-static region.

FIG. 9 illustrates a UE procedure of the dynamic TDD data channeltransmission method according to an embodiment of the present invention.

Referring to FIG. 9, the UE acquires the TDD radio frame configurationinformation and the MBSFN configuration information in the systeminformation transmitted by the eNB at step 902. Next, the UE receivesthe dynamic TDD data region configuration information at step 903. Ifthe uplink scheduling control channel is received successfully in the(m-k)^(th) subframe at step 904, the UE receives the control channel inthe m^(th) subframe at step 905. If the downlink control channel isreceived successfully in the mth subframe at step 906, the UE receivesdata in the dynamic data channel using the DMRS at step 910.

Otherwise, if the downlink scheduling control channel is not received atstep 906, the UE switches to the transmission mode at step 907 andtransmits the Physical Uplink Shared Channel (PUSCH) data channel inshortened format at step 908.

If the uplink control channel is not received in (m-k)^(th) subframe atstep 904 and if the downlink control channel is received successfully inthe m^(th) subframe at step 909, the UE receives the downlink datachannel at step 910. Otherwise, if it fails to receive the downlinkcontrol channel in the mth subframe at step 909, the UE terminatesreception session without receipt of any data.

That is, the UE checks the semi-static region and the dynamic region ofthe MBSFN subframes among a plurality of subframes multiplexedtemporally in a radio frame. The UE receives the control signal in thesemi-static region and transmits uplink data or receives downlink datain the dynamic region. At this time, the UE can transmit the uplink dataor receive the downlink data in the dynamic region according to thecontrol signal received in the semi-static region. The UE also cantransmit the uplink data or receive the downlink data in the dynamicregion of the MBSFN subframe according to the control signal carried ina static subframe linked to the MBSFN subframe among the subframes. TheUE also can transmit the uplink data in the static uplink subframelinked to the MBSFN subframe among the subframes according to thecontrol signal received in the semi-static region.

FIG. 10 illustrates a configuration of the eNB according to anembodiment of the present invention.

Referring to FIG. 10, the eNB includes a Time Division Duplex RadioFrequency (TDD RF) unit 1001, a dynamic TDD converter 1002, a CRSgenerator 1005, a control channel generator 1006, a Dedicated ModulationReference Signal (DMRS) generator 1008, a data channel generator 1009,mappers 1004 and 1007, an uplink data receiver 1011, a channel estimator1012, and a controller 1010.

The TDD RF unit 1001 is responsible for transmitting and receivingsignal in time-divided manner. The dynamic TDD converter 1002 determineswhen the TDD RF unit 1001 is used for downlink transmission and uplinkreception under the control of the controller 1010. The Cell-specificReference Signal (CRS) generator 1005 and the control channel generator1006 configure a control channel, and the DMRS generator 1008 and thedata channel generator 1009 configure a downlink data channel. Themappers 1004 and 1007 map the control and data channels in to thesubframe.

The channel estimator 1012 estimates uplink data channel according tothe uplink reference signal, and the uplink data receiver 1011 receivesuplink data. That is, when the eNB is configured to transmit the controlchannel in the semi-static region and the downlink data in the dynamicregion according to the present invention, the dynamic TDD converter1002 transmits the control channel and downlink data. If the dynamicdata channel is used for uplink transmission, the dynamic TDD converter1002 receives the uplink data.

The controller 1010 discriminates between the semi-static region and thedynamic region of the MBSFN subframes in each radio frame. Thecontroller 1010 then transmits the control signal in the semi-staticregion and receives the uplink data or transmits the downlink data inthe dynamic region. The controller 1010 can control to transmit thedownlink data in the dynamic region with DMRS. The controller 101 alsocan control to receive the uplink data using the uplink referencesignals carried in the 5^(th) and 11^(th) symbols among the 0^(th) to11^(th) symbols in the dynamic region.

The control signal can be included in the channel allocation informationfor uplink or downlink data in the dynamic region. The control signalalso can be included in the channel allocation information for uplinkdata of the uplink subframe as static region linked to the MBSFNsubframe among the subframes. The channel allocation information in thedynamic region can be transmitted through the control signal of anothersubframe as a static region linked to the MBSFN subframe among thesubframes.

FIG. 11 illustrates a configuration of the UE according to an embodimentof the present invention.

Referring to FIG. 11, the UE includes an RF unit 1101, a dynamic TDDconverter 1102, demappers 1105 and 1106, a CRS receiver 1107, a channelestimator 1108, a control channel receiver 1109, a DMRS receiver 1110, achannel estimator 1111, a Physical Downlink Shared Channel (PDSCH) datachannel receiver 1112, a data channel generator 1113, and a controller1103.

The RF unit 1101 is configured as a single device responsible for boththe signal transmission and reception. The dynamic TDD converter 1102determines the timings of uplink transmission and downlink reception ofthe RF unit 1101 under the control of the controller 1103. The demappers1105 and 1106 receive the control channel and the downlink data channel.The CRS receiver 1107 receives the common reference signal, the channelestimator 1108 estimates control channel using the common referencesignal, and the control channel receiver 1109 receives the controlchannel.

The DMRS receiver 1110 receives the common reference signal, the channelestimator 1111 estimates the downlink data channel using the commonreference signal, and the data channel receiver 1112 receives thedownlink data channel. The data channel generator 1113 generates theuplink data channel. That is, when the dynamic data region is used fordownlink transmission, the UE switches to the reception mode to receivethe control channel transmitted by the eNB. The UE receives the downlinkdata channel transmitted by the eNB. When the dynamic data region isused for uplink transmission, the UE generates uplink data channelthrough the transmission chain 1114 and transmits the uplink datachannel to the eNB.

The controller 1103 discriminates between the semi-static region and thedynamic region of the MBSFN subframe in the radio frame. The controller1103 controls to receive the control signal in the semi-static regionand transmit the uplink data or receive the downlink data in the dynamicregion. The controller 1103 can control to estimate the channel usingthe DMRS received in the dynamic region to receive the downlink data.

The controller 1103 can control to transmit the uplink data with theuplink reference signals of the 5^(th) and 11^(th) symbols among the0^(th) to 11^(th) symbols in the dynamic region. The control signal caninclude the channel allocation information for uplink data or downlinkdata in the dynamic region. The control signal can include the channelinformation for the uplink data of the uplink subframe as staticsubframe linked to the MBSFN subframe among the subframes. The channelallocation information of the dynamic region can be transmitted throughthe control information of other subframe as the static region linked tothe MBSFN subframe among the subframes.

As described above, the dynamic TDD data channel transmission method andapparatus of the present invention enables the eNB to switch theresource between uplink and downlink in the dynamic data region inadaptation to the variation of data traffic without compromising channelestimation accuracy. Also, the dynamic TDD data channel transmissionmethod and apparatus of the present invention is capable of minimizingresource waste, at the UE, caused by changing the resource in thesemi-static region.

Although embodiments of the present invention have been described indetail hereinabove, it should be clearly understood that many variationsand/or modifications of the basic inventive concepts herein taught whichmay appear to those skilled in the present art will still fall withinthe spirit and scope of the present invention, as defined in theappended claims.

What is claimed is:
 1. A method by a terminal, the method comprising:receiving system information including first time division duplex (TDD)configuration information; receiving control information via a higherlayer signaling; monitoring a physical downlink control channel (PDCCH)in a first subframe identified based on the control information; andidentifying second TDD configuration information based on the monitoringresult.
 2. The method of claim 1, further comprising: transmitting andreceiving data based on the identified second TDD configurationinformation after a second subframe.
 3. The method of claim 1, wherein,if the terminal detects downlink control information on the PDCCH, thesecond TDD configuration information is identified based on the downlinkcontrol information.
 4. The method of claim 1, wherein, if the terminaldoes not detect downlink control information on the PDCCH, the secondTDD configuration information is the same as the first TDD configurationinformation.
 5. The method of claim 1, wherein the control informationis included in a radio resource control (RRC) message.
 6. A method by abase station, the method comprising: transmitting system informationincluding first time division duplex (TDD) configuration information;transmitting control information via a higher layer signaling;transmitting downlink control information on a physical downlink controlchannel (PDCCH) in a first subframe identified based on the controlinformation, wherein the downlink control information is used toidentify second TDD configuration information.
 7. The method of claim 6,further comprising: transmitting and receiving data based on theidentified second TDD configuration information after a second subframe.8. The method of claim 6, wherein, if the downlink control informationis detected on the PDCCH, the second TDD configuration information isidentified based on the downlink control information.
 9. The method ofclaim 6, wherein, if the downlink control information is not detected onthe PDCCH, the second TDD configuration information is the same as thefirst TDD configuration information.
 10. The method of claim 6, whereinthe control information is included in a radio resource control (RRC)message.
 11. A terminal, comprising: a transceiver configured totransmit and receive a signal; a controller configured to receive systeminformation including first time division duplex (TDD) configurationinformation, receive control information via a higher layer signaling,monitor a physical downlink control channel (PDCCH) in a first subframeidentified based on the control information, and identify second TDDconfiguration information based on the monitoring result.
 12. The methodof claim 11, wherein the controller is further configured to transmitand receive data based on the identified second TDD configurationinformation after a second subframe.
 13. The method of claim 11,wherein, if the terminal detects downlink control information on thePDCCH, the second TDD configuration information is identified based onthe downlink control information.
 14. The method of claim 11, wherein,if the terminal does not detect downlink control information on thePDCCH, the second TDD configuration information is the same as the firstTDD configuration information.
 15. The method of claim 11, wherein thecontrol information is included in a radio resource control (RRC)message.
 16. A base station, comprising: a transceiver configured totransmit and receive a signal; a controller configured to transmitsystem information including first time division duplex (TDD)configuration information, transmit control information via a higherlayer signaling, and transmit downlink control information on a physicaldownlink control channel (PDCCH) in a first subframe identified based onthe control information, wherein the downlink control information isused to identify second TDD configuration information.
 17. The method ofclaim 16, wherein the controller is further configured to transmit andreceive data based on the identified second TDD configurationinformation after a second subframe.
 18. The method of claim 16,wherein, if the downlink control information is detected on the PDCCH,the second TDD configuration information is identified based on thedownlink control information.
 19. The method of claim 16, wherein, ifthe downlink control information is not detected on the PDCCH, thesecond TDD configuration information is the same as the first TDDconfiguration information.
 20. The method of claim 16, wherein thecontrol information is included in a radio resource control (RRC)message.